Liposomes have been studied for the purposes of treating various diseases. Liposomes are valuable materials for delivering a therapeutic drug or an active agent to a selected target site in vivo because they are microcapsules constituted of lipid and having a particle size on the order of nanometers, can encapsulate various compounds and the like in the microcapsule, and have excellent biocompatibility and the like. For such a purpose, large unilamellar vesicle liposomes (LUV) having an average particle size of 100 nm or more are generally used, and various materials have been developed as materials constituting such a membrane.
Such a liposome can be constituted of one type of lipid. As the lipid in such a case, for example, a phospholipid having a head and a hydrophobic tail bound thereto is used, and these lipids associate to form a membrane, which constitutes a microcapsule capable of encapsulating an active agent and the like. In order to add the remarkable characteristics to a liposome, however, a lipid mixture for constituting a liposome is generally used. The lipid mixture contains a mixture of: a lipid having excellent biodegradability; a lipid for suppressing the aggregation of liposome to be formed; a lipid having an effect of suppressing the leakage of the encapsulated matter; a lipid having an effect of membrane fusion; and the like.
Each lipid has been studied in order to enhance the characteristics of a liposome. For example, a medical liposome dedicated to gene transfer preferably satisfies high biodegradability, high biocompatibility, high ability to transfect an active agent, and low cytotoxicity, and then lipids that can constitute such a liposome are desired.
Various compounds have been developed as such lipids, but there is a great diversity in the state of an organism which the compounds are applied to and in diseases to be treated. It is desirable to have more types of lipids among which to select in accordance with these conditions. Furthermore, there is a demand for lipids that can constitute a liposome having characteristics surpassing those of conventional liposomes.
Against the above-mentioned problems, the present embodiment is to provide: a novel compound as a lipid capable of constituting a liposome; and a lipid particle for which the compound is used; and a composition and a kit.